Alternating between Primary and Backup LS-Quad

[arowana1]

   

i have 2 units of LS-Quad (lets call it A and B).  A is now my primary unit and i have configured it to do a Complete/Differential backup to B.  it is now running into its 2nd day, trying hard to backup 1.3tb of data.  i tink it is going at around 300gb /day.

 

wat i would like to do is to alternate the use of A and B.  when A completes the backup to B, i would like to use B as my primary.

 

question 1:  if i remove the backup schedule in A and put this schedule in B to backup to A, will the backup to a differential or will it do a FULL backup again since it is now the other way round?

 

question 2:  for complete/differential backup, or any of the backup options for that matter, how does ls identify if a file has changed?  based on file date/time, size or does it keep a backup log?  i assume if it goes by a backup log method, then question 1 is that it will do a FULL backup again if i reverse A and B.

 

question 3:  if question 1 is possible, i.e. i switch from A to B, then it is also possible for me to switch from B to A anytime i want.  all i need to be careful with is which way my backup is going.

 

thanks in advance!